A/C condensor over fused

On my morning inspection today I ran in to this Lennox condenser that was rated for a 40amp fuse. The service disconnect had a 60 amp installed. Check out the wire above the lug on the right.


So, an overcurrent was applied to the breaker and the breaker did not trip. The wire got hot and melted the insulation. If you were asked to write a paragraph describing the sequence of events leading up to this, what would you say. What possible scenerios would cause the condensor to attempt to trip the breaker? Just hungry for knowledge and understanding.



I am not really sure. Although I am curious myself as to why it happened, my duty as a home inspector is not to speculate on the reason but to inform my clients of the problem. I recommended that have a HVAC guy check it out for them.
I am sure there a many reasons why it could have happened ranging from a loose connection at the lug to a compressor that was on it’s last leg.

If the unit still operates it is typically just a loose connection that heated up the wire.

Oh yeah, I forgot to mention that when I pulled up to the house the home owner had a friend over that was adding freon to the system. I watched him for a minute and when I got out my truck they quickly disconnected the gages and the friend left. They did not say anything about it and I did not ask. Yet another reason I recommended the HVAC guy.

Many homeowners have slow leaks in their hvac systems and just get them charged up when needed. Sometimes they have had the system worked on and know that the leak can not be found by the tech. or that the cost to replace the coil is too much. Looks like you found one of those…
Were you early arriving there when you saw them working on it?

This home was number 1 of 3 for the day. I was scheduled to arrive at 9:00 am but I was trying to get a jump on the day and arrived 20 minutes early. The guy adding the freon was in street clothes driving a car.

If you look very close to the number of strands of the white wire it appears to be missing some…hmmm
I would venture to say that the full diameter of the wire (strands) are not under that screw thus making a smaller wire handle the larger amperage…

Maybe when that was installed , during the stripping of the end someone nicked or cut strands by error and figured it would not be a problem…:wink:

2nd phase definitely missing strands, possible loose connection or a phase imbalance. Still needs to be called out and inspected by HVAC professional.